Method of and heans for drying out and impregnating joints for cables



Dec. 8, 1931.

a. ZEISS El AL 1,835,922

METHOD OF AIDIIMIS FOR DRYING OUT AND IIPREGNA'I'ING JOINTS FOR CABLES Filed March 14, 1929 ---o 1 I n Invent ors:

Bruno Zeiss, Alfons Moll,

Their Attorq eg Patented Dec. 8, 1931 .iiTATES BRUNO ZEISS, OF BERLIN-MAKLSDORF-SUD, AND ALFONS MOLL, OF BERLIN, GERMANY, ASSIGNOBS TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK METHOD OF AND IiEANS FOR DRYING OUT AND IMPREGNA'I'ING JOINTS FOR CABLES Application filed March 14, 1929, Serial No. 347,045, and in Germany September 28, 1928.

As is well known, the joints used for electrically uniting the sections of high tension underground cables are insulated by winding over the connector which unites the conductors and the adjacent ends of the cable sections a paper ribbon to a thickness generally in excess of the insulation on the cable itself. The fact that these joint windings are generally done by hand and as a rule under lo very unfavorable circumstances, being' done in manholes where there is considerable moisture, and in some cases water, has the result that considerable moisture and a small amount of air are present in the finished joint which can only be removed with great difficulty, The method of treating the joint by uuin and heating the cable in order to increase the evaporation of the moisture has been employed, but experience shows that after the introduction of the fluid filling there still remains some moisture in the joint which after the filling operation cannot be removed.

ed and meausfor nd air nvention has for its object to "7; lll

removing any entrained moisture a the joints of a high tension cable sys' tem.

'ideratiou of What we believe to id our invention, attention is di acconpanying description and appcn l. thereto.

sawing is illustrated a, cable goint for removing any entrained moiswhich may be present.

n indicate the adjacent ends of sechigh "tension underground cable, being a part of: a. system composed .erous sections. Each section has a tor, insulation the on and an enclosic lead or semi noicatcs .lTL this CfiSLi and the insu. n W} a ping around the connector that the present ration directcc. For this purpose an opening is provided in the upper side of the casing and attached thereto is an elevated filling vessel 6 of any suitable construction. It is provided with one or more sight openings which have glass covers 7. To the casing are attached suit-able gauges 8 and 9, one for vacuum and the other for pressure. The top of the vessel has a short pipe 10 which is used in filling the-vessel and also to receive the suction-pipe of a vacuum pump 10a for evacuating the casing. It is also used for a pressure pump which may also be indicated by the reference character 10a. The lower side of the casing is provided with an opening to receive the pipe 11. 12 indicates a vessel which contains fluid for filling the' joint and is heated by a gas burner 13 or other source of heat. This vessel is connected at its lower end to the pipe 11 and at its upper end by the pipe 14 to the vessel 6. In the pipe 11 is a shut-off valve 15. 16 indicates a pressure pump which ma be handoperated by asuitable lever and w iich is connected in shunt to the valve whereby when the valve is shut fluid may be positively circulated through the casing 5, the filling vessel 6 and the heating vessel 12.

The joint having been properly taped and the casing sweated or otherwise secured fluidtight to the cable sheaths, the operation is as follows: Fluid is poured into the vessel 6 through the filling opening 10. It first flows through the casing 5 and pipe 11 into the heating vessel 12, and later gradually rises in the latter and pipe 14 until it returns to the filling vessel. The filling process is continued until the level reaches the inspection windows 7Q \Vhen the fluid is thinned sufii ciently by reason of the heat supplied by the burner, it flows upward by convection through the pipe 14 into the filling vessel and there 3y starts an automatic circulation through the vessels and casing. If the process proceeds too slowly it can be artificially accelerated by temporarily closing the valve and operating the pump 16. The exit of the water vapor can be recognized by the mist forming on the level surface of the fluid in the filling vessel and may be observed through the inspection or sight openings 7.

ing.

The removal of the water vapor and air may be hastened by connecting a vacuum pump to the short pipe 10 at the top of the filling vessel.

After the fluid, sleeve and associated parts are relatively cool, .the pipe 11 is removed and the opening therefor in the casing sealed. The vacuum pump connection is then broken and a pressure pump connected to the conduit 10'and fluid which has previously been degasified forced under pressure into the cas- This subsequent submission of the parts'to fluid under pressure insures greater security against the, inclusion of air than would otherwisc'be the case.

-. The method andi apparatus'herein describedare useful also'in making end sealings for the cable as well as for cable fillings r and. other purposes.

' The heatdue to the burner 13 causes the fluid to-circulate due to convection currents an'd theoperation is continued until all or the principal part of the entrained gas and mois- "ture is removed. This operation isfacili- 25,v

tated by the use'of the vacuum pump which maintainsa pressure within the casingwhich is bGlOu-{lillflll of the atmosphere. During the oper'ationthe paper-or other wrapping on the cable joint is thoroughly impregnated with the fluid.

lVhat we claim as-new and desire to secure by Letters Patentof the United States is 1, The method of drying-out and impregnating theinsulation of a'cabl jointwhich admission of gas and moisture.

comprises filling the joint enclosing casing with fluid, repeatedly circulating hot fluid therethrough; subjecting the casing and the fluid during the period of circulation'to vacuum to assist in the removal of gas and moisture, and finally sealing said casing when parts.

3. The method of dryingout and impreg nating'the insulation of a cable joint which comprises connecting fluid filling and heating vessels to the casing of the joint in a manner to cause fluid to flow through the vessel and easing by convection, maintaining a forced circulation through the vessels and casing until the fluid is thoroughly heated, removing the vessels. and sealing the casing to prevent theescape of fluid and the 4. The method of drying out and imprcg nating the insulation of cable parts which comprises circulating heated fluid through the casing of said parts to remove gas and moisture, partially cooling the parts, subsequently subjecting the fluid in the casing to pressure, and finally sealing the casing.

5. The method of drying out and impregnating the insulation of cable parts which comprises connecting fluid filling and heating vessels to said parts in a manner to cause the fluid to flow through them by convection, removing the vessels, sealing the cable parts except for one opening, establishing a pressure on the fluid in the parts after they are relatively cool, and sealing the said opening.

6. Apparatus for drying out and impregnating the insulation of cable parts which 30 are enclosed in a metal casing, comprising, a fluid filling vessel situated above and connected to the casing, a heating vessel situated below and connected to the casing at a lower point, means for heating the latter vessel, and a connection between the two vessels to permit the flow 0f fluid from the heating vessel to the filling vessel by convection.

7. Apparatus for drying out and impregnating the insulation of cable parts which I are enclosed in a metal casing, comprising, a fluid filling vessel situated above and connected to thecasing, a heating vessel situated below and connected to the casing at a lower point, a shut-ofl' valve in the connection between the heating vessel and the casing. a circulating pump arranged in shunt to the valve. means for heating the last named vessel. and a connection between the two vessels which permits the fluid to circulate by con-' vection when said valve is open.

In witness whereof. we have hereunto se our hands this 19th dav of February, 1929'.

BRUNO 'ZEISS.

ALFONS MOLL. 

